While Claude is not yet available, there are tight rate limits on o1-preview (~10 messages in a 15 minute window); this is low enough that it hampers anything close to "flow".
You can't switch models inside a single request, and it does not follow Aider's clear split (in Architect mode) between "plan" and "implement". If Copilot Editor decides to start implementing file changes alongside its response, you can hit your entire o1-preview cap in a single request-response pair.
When it does work, it's like Aider inside your IDE.
Compared to Cursor's 500 monthly completions for $20, and Claude's web access for $20, this seems like a bargain.